淮南煤田煤中后生矿物成因及其地球化学意义研究

The Huainan coalfield, which is located at the southern margin of the North China coal accumulating basin and is commonly intruded by magma in the northern part, is an important energy resource base in eastern China. Due to the relatively complicated geologic conditions, many epigenetic minerals, which are hosts of certain hazardous trace elements, were widely deposited in the Huainan coal, including epigenetic kaolinite, siderite, quartz, pyrite, and Fe-bearing dolomite. However, its origin and geochemical significance are still unclear. Therefore, the genetic mechanism (i.e., origins, compositions, temperatures, and sequences of the mineralizing fluids) and geochemical implications (e.g., their impacts on the enrichment of certain trace elements) of epigenetic minerals in the Huainan coals will be investigated by coal geological, mineralogical, and geochemical methods. Specifically, the occurrence, distribution, chemical composition, carbon, oxygen, and sulfur isotopes of the epigenetic minerals and the concentrations of trace elements in bulk coals will be analyzed. Finally, the general formation mode of epigenetic minerals and the corresponding geochemical response mechanism of coal will be discussed.

淮南煤田是华东重要的能源基地之一，地处华北聚煤盆地南缘，煤系地层沉积于滨海过渡环境，且其北部岩浆岩广泛发育，侵入煤层，较为复杂的地质背景导致煤中大量后生矿物沉积；后生矿物可能是某些有害元素的载体，从而影响煤炭资源的清洁利用和共伴生矿产资源的勘探。前期发现淮南煤田煤中赋存有高岭石、菱铁矿、石英、黄铁矿及含铁白云石等多种后生矿物，其成因机制及地球化学意义不明。本课题拟以淮南煤田煤中后生矿物为研究对象，结合煤地质学、矿物学和元素地球化学等理论，分析其赋存形态、分布特征、元素组成、碳、氧和硫同位素组成，从而揭示其成因——矿化流体的来源、组成、温度、阶段性等，进而研究其地球化学意义——对煤中微量元素的潜在影响，探讨矿化流体、后生矿物和煤中元素之间的耦合关系，最终归纳出后生矿物的成因模式及煤地球化学的响应机理，丰富煤地质学理论。

淮南煤田是华东重要的能源基地，地处华北聚煤盆地南缘，煤系地层沉积于滨海过渡环境，且其北部岩浆岩广泛发育，较复杂的地质背景导致煤中高岭石、菱铁矿、石英、黄铁矿及铁白云石等后生矿物沉积，其成因机制及地球化学意义不明，后生矿物还可能是某些有害元素的载体，从而影响煤炭资源的清洁利用和共伴生矿产资源的勘探。. 项目以淮南煤田煤中后生矿物为研究对象，结合煤地质学、矿物学和元素地球化学等理论，分析其赋存形态、分布特征、元素组成、碳和硫同位素组成，从而揭示其成因——矿化流体的来源、组成、温度、阶段性等，进而研究其地球化学意义——对煤中微量元素的潜在影响，探讨矿化流体、后生矿物和煤中元素之间的耦合关系，最终归纳出后生矿物的成因模式及煤地球化学的响应机理。. 项目分别测定了后生方解石和黄铁矿的碳和硫同位素组成，表明煤中方解石是由岩浆侵入煤接触热变质作用产生的CO2与含钙热液作用沉积，而黄铁矿由富Fe2+热液与煤接触变质过程中产生的挥发性硫反应沉积；热液流体主要有两期，一期为富Ca2+和Fe2+热液流体，导致方解石、铁白云石和黄铁矿部分充填裂隙和脱挥发孔；二期为富Si热液流体，导致石英沉积，部分包裹方解石和黄铁矿；根据后生矿物带能谱的扫描电镜和煤样微量元素的测试分析，发现煤中仅V和F稍富集，淮南煤田两期热液流体对煤的地球化学特征影响较小；淮南煤田煤系共伴生矿产资源应重点关注铝土矿层和太原组灰岩岩浆侵入部位。. 该项目成果为淮南煤田煤炭资源的清洁利用和煤系共伴生资源勘探提供了理论支持。